Writing in the journal Nutrients, researchers in Iran and Japan explored the effects of dark chocolate in CrossFit athletes during the four phases of the cycle: menstrual, follicular, luteal and premenstrual syndrome (PMS).
“The findings may yield practical applications for female-centered sports nutrition and contribute to personalized recovery strategies in high-stress, performance-driven environments,” they wrote.
Dark chocolate for female Crossfit athletes
CrossFit is designed to boost performance across strength, endurance, power and agility, combining functional movements at high intensity with minimal rest. While the fitness benefits are clear, it can often cause exercise-induced muscle damage (EIMD) due to the mechanical and metabolic stress exceeding muscle adaptation capacity.
EIMD manifests through muscle soreness, weakness and inflammation, marked by elevated levels of CK, LDH, myoglobin and inflammatory markers like CRP, IL-6 and TNF-α. These effects can hinder recovery and performance, especially in female athletes who experience hormonal fluctuations throughout the menstrual cycle.
Hormonal changes can affect metabolism, thermoregulation, neuromuscular coordination and fatigue levels. The follicular phase which involves increased estrogen levels, can support performance by improving muscle recovery, protecting joints and bones, and enhancing cardiovascular and metabolic efficiency.
On the other hand, increased progesterone in the luteal and premenstrual phases can reduce coordination while increasing fatigue and sensitivity to pain. PMS symptoms, such as mood swings, discomfort and cognitive challenges, can further impact training outcomes.
CrossFit promotes aerobic and anaerobic adaptations, enhancing mitochondrial capacity and lactate tolerance, but also raises oxidative stress and inflammation, effects which are amplified by menstrual cycle-related hormonal shifts.
Dark chocolate, due to its rich flavonoid composition of epicatechin and catechin, may offer antioxidant, anti-inflammatory and neuroprotective benefits, and research has suggested that it could improve blood flow, reduce muscle soreness and support cognitive and metabolic function during exercise. It also contains beneficial nutrients such as magnesium and theobromine, which may ease menstrual pain and stabilize mood.
Boosting cognitive performance and endurance
The researchers recruited 15 trained female CrossFit athletes, who were screened six months prior using the Premenstrual Symptoms Screening Tool (PSST) to assess menstrual cycle regularity and PMS symptoms.
The participants completed standardized sessions to practice cognitive and physical tests and were randomly assigned to one of three conditions: 85% dark chocolate (30 g/day), placebo or control. Each intervention lasted one menstrual cycle of 28 days, with testing during each of the phases and with two-month washout periods between each. For three consecutive days of each menstrual phase, participants consumed either dark chocolate or a placebo.
Performance assessments mimicked CrossFit training sessions. Delayed-onset muscle soreness (DOMS) was measured using a 100 mm visual analog scale (VAS) before, immediately after and at 12, 24, 48 and 72 hours. Handgrip strength (HGS) was assessed using a calibrated hydraulic dynamometer, and a Stroop test assessed cognitive function through reaction time (RT).
Findings indicated that dark chocolate enhanced high-intensity functional exercise performance across all menstrual cycle phases compared to placebo and control conditions. The benefits were most noticeable in the PMS phase, where dark chocolate improved cognitive function, with participants showing faster reaction times and better accuracy on the Stroop test. However, it had little effect on HGS and only slightly reduced DOMS during the luteal phase.
The researchers noted that the results suggest that while acute dark chocolate supplementation boosts endurance-type workout performance and cognitive abilities in female athletes, its effects depend on the menstrual cycle, with the greatest benefit occurring in the late luteal phase. Furthermore, supplementation did not impact muscular strength, suggesting that its ergogenic benefits are more relevant for metabolic and neuromuscular endurance rather than maximal force production.
According to the study, cocoa flavonols may enhance cerebral blood flow and oxygenation, boost cognitive performance and enhance cardiovascular and metabolic function as epicatechin promotes nitric oxide production for better muscle blood flow, improved endurance and delayed fatigue during exercise. In addition, the antioxidants found in dark chocolate may help mitigate oxidative muscle damage and soreness, particularly during the luteal phase.
The researchers called for future studies to consider larger samples, hormonal profiling and long-term interventions to confirm the observations.
Source: Nutrients 2025, 17(8), 1374. door: https://doi.org/10.3390/nu17081374. “Dark Chocolate Mitigates Premenstrual Performance Impairments and Muscle Soreness in Female CrossFit Athletes: Evidence from a Menstrual-Phase-Specific Trial”. Authors. Safari, K. et al.